1. Field of the Invention
The present invention relates to a switching power supply control circuit, and more particularly, to the control circuit of a current mode switching regulator having a switching element and a smoothing circuit.
2. Description of Related Art
Switching regulators are known as voltage mode, current mode, or the like from the standpoint of the control system. The voltage mode is known to usually have simple control, but a complicated phase compensation circuit. The current mode, on the other hand, is known to have more complicated control, but a greatly simplified design of the phase compensation circuit. The current mode is also known to have line regulation; that is, little change in the output voltage when the input voltage of the switching regulator is changed.
Japanese Laid-Open Patent Publication No. 2012-110119 has claimed to reduce oscillation of the output of a power supply circuit operated by the current mode without using a high-precision DAC. Japanese Laid-Open Patent Publication No. 2000-287439 relates to a current mode switching regulator, in which a signal expressing an inductor current is offset so as not to reach a command value in the case that the signal has noise. Japanese Laid-Open Patent Publication No. 2009-254047 has offered a variety of circuits configured to convert a current flowing into an inductor of a switching regulator to a voltage. In the related art, a digital-analog converter configured to convert a digital signal to an analog signal is commonly called a “DAC” and an analog-digital converter configured to convert an analog signal to a digital signal is commonly called an “ADC,” and these terms will be employed in this application.